Helm is an incremental completion and selection narrowing framework for Emacs. It can be seen as a set of tools with an interactive interface that will help steer you in the right direction when you're looking for stuff in Emacs (like buffers, files, etc).

Helm is a fork of anything.el originally written by Tamas Patrovics and can be considered to be its successor. Helm sets out to clean up the legacy code in anything.el and provide a cleaner, leaner and more modular tool that's not tied in the trap of backward compatibility.

Usage

Useful Keybindings

mark candidates. This is useful when you need to perform an action on many candidates of your choice. M-a to select all.

[C-c C-i]

insert candidates in the current buffer.

[TAB]

access to the actions menu. An action is a command to run on marked candidates (one or more) and quit current Helm session; an action menu is a text-based menu that lists actions you can take. For example, Find File (open file), Find File in Dired, Grep File, etc.

[C-z]

executes helm-execute-persistent-action. A persistent action is an action that you use in a Helm session without quitting the session.

[C-t]

toggle the horizontal and vertical view.

[C-c ?]

show help

In some Helm session, such as helm-find-files or helm-mini, you can select more than one candidates and execute actions on them, such as grep or open.

Use regular expressions

The matching mecanism uses regular expressions.

For example, in M-x helm-M-x, typing pack ^li will suggest

list-packages

at first.

Operate on text at point

If you are already in a Helm session, you can still get input from the current editing buffer by the following key bindings:

[C-w]

yanks word at point, starting from point to the end of the word, into the Helm prompt (the minibuffer).

[M-n]

yanks symbol at point

Example commands

The extensive list of available commands is listed on their wiki. Some common ones are:

helm-find-file: navigate in your file hierarchy

Many actions are available with the TAB key (open, find file in Dired, grep selected files, open as root, copy files, etc). You can also view the full list of action keys with C-c ?.

You can view images with C-u C-z on an image file, and start follow mode with C-c C-f. It uses image-dired in the background.